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SPARC: add the Flush windows software trap

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This commit implements the SPARC V8 ABI "Flush windows" software trap.
It enables support for C++ exceptions and longjmp().

Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>
This commit is contained in:
Martin Åberg 2021-05-27 18:05:33 +02:00 • committed by Kumar Gala
commit aa0a90d09c
2 changed files with 69 additions and 2 deletions
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2
arch/sparc/core/trap_table_mvt.S
View file

@ -52,7 +52,7 @@
#define WOF_TRAP TRAP(__sparc_trap_window_overflow) #define WOF_TRAP TRAP(__sparc_trap_window_overflow)
#define WUF_TRAP TRAP(__sparc_trap_window_underflow) #define WUF_TRAP TRAP(__sparc_trap_window_underflow)
#define FLW_TRAP BAD_TRAP #define FLW_TRAP TRAP(__sparc_trap_flush_windows)
#define INT_HANDLER __sparc_trap_interrupt #define INT_HANDLER __sparc_trap_interrupt
#ifdef CONFIG_IRQ_OFFLOAD #ifdef CONFIG_IRQ_OFFLOAD

69
arch/sparc/core/window_trap.S
View file

@ -6,14 +6,17 @@
/* /*
* This file contains standard handlers for the SPARC V8 window overflow and * This file contains standard handlers for the SPARC V8 window overflow and
* underflow traps. * underflow traps. It also implements the handler for SPARC-ABI
* "Flush windows" which is used for example by longjmp() and C++ exceptions.
*/ */
#include <toolchain.h> #include <toolchain.h>
#include <linker/sections.h> #include <linker/sections.h>
#include <arch/sparc/sparc.h>
GTEXT(__sparc_trap_window_overflow) GTEXT(__sparc_trap_window_overflow)
GTEXT(__sparc_trap_window_underflow) GTEXT(__sparc_trap_window_underflow)
GTEXT(__sparc_trap_flush_windows)
SECTION_FUNC(TEXT, __sparc_trap_window_overflow) SECTION_FUNC(TEXT, __sparc_trap_window_overflow)
/* Enter the window to be stored. */ /* Enter the window to be stored. */
@ -73,3 +76,67 @@ SECTION_FUNC(TEXT, __sparc_trap_window_underflow)
/* Re-execute restore. */ /* Re-execute restore. */
jmp %l1 jmp %l1
rett %l2 rett %l2
/*
* Handler for SPARC trap 0x83: trap_instruction, defined as "Flush windows" by
* SPARC-ABI:
* "By executing a type 3 trap, a process asks the system to flush all its
* register windows to the stack."
*
* This implementation uses the window overflow trap handler to perform the
* actual window flush.
*
* On entry:
* %l0: psr
* %l1: pc
* %l2: npc
*/
SECTION_FUNC(TEXT, __sparc_trap_flush_windows)
/* push a few registers which are needed later to the stack */
sub %sp, 0x10, %sp
std %l0, [%sp + 0x40 + 0x00]
st %l2, [%sp + 0x40 + 0x08]
st %g2, [%sp + 0x40 + 0x0c]
restore
/* In window where we trapped from. This window will not be flushed. */
/* Set highest processor interrupt level and enable traps. */
rd %psr, %g2
or %g2, PSR_PIL, %g2
wr %g2, PSR_ET, %psr
nop
nop
/* Execute "save" NWINDOWS-1 times. */
set CONFIG_SPARC_NWIN-2, %g2
1:
save
cmp %g2, %g0
bne 1b
sub %g2, 1, %g2
/* Execute "restore" NWINDOWS-1 times. */
set CONFIG_SPARC_NWIN-2, %g2
2:
restore
cmp %g2, %g0
bne 2b
sub %g2, 1, %g2
save
/* pop registers from stack which are used for the trap return */
ldd [%sp + 0x40 + 0x00], %l0
ld [%sp + 0x40 + 0x08], %l2
ld [%sp + 0x40 + 0x0c], %g2
add %sp, 0x10, %sp
/* Restore %psr as it was on trap entry. */
wr %l0, %psr
nop
nop
nop
jmp %l2
rett %l2 + 4